Top lead locator



Feb. 1960 c. J. SCHNERING 2,923,098

TOP LEAD LOCATOR Filed Nov. 18, 1955 5 sheets sheet 1 LOADING FIE- (D ED O z D O D- "s INVENTOR m CHARLES J. SCHNERING ATTORN Feb. 2, 1960 c.J. SCHNERlNG 2,923,098

TOP LEAD LOCATOR Filed Nov. 18, 1955 5 Sheets-Sheet 2 INVENTOR CHARLESJ. SCHNERING ATTOR Y Feb. 2, 1960 c. J. SCHNERING 2,923,093

TOP LEAD LOCATOR Filed Nov. 18, 1955 5 Sheets-Sheet 5 INVENTOR CHARLESJ. SCHNERING ATTORag United States Patent TOP LEAD LOCATOR Charles JohnSchnering, Lock Haven, Pa., assignor, by mesne assignments, to SylvaniaElectric Products Inc., Wilmington, Deb, a corporation of DelawareAppiication November 18, 1955, Serial No. 547,642

1 Claim. (Cl. 49- 2) This invention relates to electron tube manufactureand in particular to the sealing in of a top terminal within the dome ofa glass envelope.

in certain types of electron tubes it is desirable to provide a terminallead which shall extend through the dome of the envelope in addition tothe circularly arranged leads at the base of the tube. Typical of thisclass of tubes are the beam power and diode rectifier types wherein ananode lead is led through the dome, although it should be noted thatthis invention is not restricted to these specific types of tubes. Wherea lead does extend through a dome, cracks are apt to develop in theglass if the lead is not centered in the dome. These cracks are due tounequal distribution of the mass of the glass about the lead or tostrains on the lead after a cap and connector has been applied to theterminal. Moreover unsymmetrical centering of the top lead is unsightlyand renders the article less salable.

This off centering is apt to occur because only the lower end of thelead is fixedly mounted within the tube, the upper terminal of the leadfloating through a comparatively large opening in the dome of theunfinished tube. As a consequence, when the glass around the opening isfused down about the terminal there is no certainty that the lead willbe axial of the tube.

The object of the invention is to provide a simple means to insure theaxial arrangement of the top lead seal with respect to the longitudinalaxis of symmetry of the tube.

It is a further object of the invention to accomplish this purpose withas few changes on existing equipment as possible.

These and other objects will be made clear by consideration of thefollowing specification and claim when taken in connection with theaccompanying drawings in which:

Fig. l is a diagram illustrating the method of sealing the top leadwithin an envelope as well as the sealing of the bulb to its stem.

Fig. 2 is a fragmental portion of the machine showing a tube in placeprior to sealing of the glass of the dome about the top lead, partsbeing shownin section.

Fig. 3 is a section on the line 3--3 of Fig. 2 looking upward with partsof the tube broken away to better expose top lead centering parts of thenew device, and

Fig. 4 is a perspective view of a preferred embodiment of the wireguiding attachment.

Referring to the drawings with greater particularity and with immediatereference to Fig. 1, there is diagrammatically illustrated part of asixteen position electron bulb sealing machine which functions to sealthe bases of bulbs to stems or Wafers which support the tube electrodesin proper spaced relationship to one another. For each machine positionthere is a tube peg for supporting the assembled parts of a tube and acooperating head for centering the bulb during the time the bulb isbeing fused to the stem and while the top lead is sealed in the dome ofthe bulb. The heads and pegs are Patented Feb. 2, 1960 all indexed aboutthe machine, both heads and pegs rotating together at all stationsexcept at station No. 16 which is the unloading station, station No. 1which is the loading station, and station No. 2 at which the operatormay adjust tube parts. In the diagram, the bulb is designated as 10 andthe wafer stem with its electrode mount is indicated at 12. As anexample, a type of electron tube is selected which comprises an anode 14to which is welded a long bent lead-in wire 16, this lead-in wireextending through a preformed opening 18 within glass collar 20 formedon the dome 22 of the bulb. Prior to this invention, the operator, whenloading the tube on a sealing peg 24 at the first or loading position ofthe machine, essayed to center the wire 16 within collar 20 by manualoperation, but was not always successful. With the device of thisinvention no such manual centering is necessary, as will be made clear.In the operation of the machine, after loading the machine at stationNo. l, the machine indexes, and the bulb and stem assembly are lifted byreason of cams (not shown) acting on the pegs, bringing the tube nearerto the head. At station No. 2 the operator still has an opportunity toposition parts on the peg. At station No. 3 the tube assembly is raisedto an elevation'such that the bulb is positioned centrally of the stemassembly by a pair of arms 26 mounted on the head 28 of the machine. Itshould be noted that the bottom :of the bulb rests on top of the stemassembly which keeps the bulb upright and the arms will assist incentering the bulb on the assembly. At this station the lead-in 16 isnot yet centered by the machine. However, at this station rotation ofthe peg and head is initiated and preheating flames are applied to thejuncture of the glass bulb and wafer. All of the mechanisms operating onthe tube at stations No. 1 to No. 3 are old in the art and therefore nofurther description of the machine as to these features is deemed to benecessary herein. At station No. 4 a change in the mode of treatment ofthe sealing in of the lead-in wire does take place. At this station, asis conventional, the tube peg is raised to its maximum height bringingthe bulb it well in between the centering arms .26. Here the wire 16enters a novel element attached to the head, the same comprising athimble 3th in the form of a conical guide provided with a, centralaperture through which the lead-in wire 16 extends. This guide centersthe Wire'within the collar 20. At this station, as is conventional inthe art, further preheating fires play on the bulb and wafer. Atsubsequent stations, preheating and pin point fires play on the bulbboth at the bulb-wafer juncture and at the juncture of the glass collar20 and the lead-in wire 16. Toward the final index stages of themachine, annealing fires are played on the seals while the peg lowerswith its sealed tube. Usually at the station penultimate to unloading(station No. 15), no fires are played on the bulb but it is stillrevolved to allow the tube to set to symmetrical shape and to cool thesame. At positions No. 14 and No. 15, it is no longer necessary to holdthe lead-in wire in position since the seal of bulb dome to wire hasalready been effected. The sealed bulb and stem with sealed in anodelead-in wire is removed at station No. 16. Subsequently a cap is slippedover the end of the wire 16, adhered to the bead formed at the lead-inseal and soldered to the lead-in wire, as is customary in the art.

A specific means employed to center the lead-in wire is illustrated inFigs. 2, 3, and 4. In these figures there is shown at 28 one of therotatable heads of the sealing machine, the same being supported by oneof the machines head supporting arms 32, the head being rotated by achain mechanism 33 in housing 34 driving a shaft 36 to which the head 28is fixed as by a bulb 38. The head is conveniently in the form of aspider with three fingers 40 in which are fixed posts 42, 44, and 46,respectively. These posts are supplied for such aflixations thereto asmay be desired. In this embodiment post 42 has suitably afiixed theretothe arms 26. One of these arms indicated as 48 in Figs. 2 and 3, isfixedly secured to post 42 by a hex nut 50. The other arm is suitablyrotatably mounted on the post and is provided with a bulb engagingroller 54, this arm being spring pressed toward the arm 48 by a spring56 having one end operating on an' extension 58 from arm 52 and anchoredat its other end to a pin 60 extending from a finger 40. No novelty isclaimed as to the use of these bulb centering arms per se, since theyare part of the prior art. However, as the bulb, seated on the peg 24 islifted up, the dome of the bulb slides against the fixed arm end 48while the arm 52 yields so that the roller 54 presses the bulb lightlyagainst the end 48. These arms serve to center the bulb so that thelead-in centering device when centering the wire with respect to thelongitudinal axis of the tube will also center it with reference to thelongitudinal axis of the bulb.

The lead-in centering device is supported from a plate 62 provided withholes 43 and 47 to snugly embrace the posts 42 and 46 and clamped to theposts by cap screws 64 or the like. The plate has an arcuate recessedportion 66 adapted to surround the hub portion of the head 28 and apositioning recess 68 at the rear edge of the plate. Positioned by thisrecess is a vertical support bar 70, which is provided at the upper endwith an elongated slot 72 through which a screw is passed and threadedinto the rear edge of the plate to hold the bar in selected verticalposition in accordance with the height of the upper end of the lead-inwire to be guided. The bar is furnished at the lower end with anenlarged foot 74 provided with a recess to position a guide holdingcantilever 76, this cantilever having a slot 78 at its rear end throughwhich a screw 80 is passed to adjustably position the cantilever. At thefront end of the cantilever is a bore accommodating the thimble 30. Thethimble 30 is circular in horizontal cross section with a flange 82engaging the lower surface of the cantilever, and held in the bore by aset screw 84 or the like. The interior of the thimble has an upwardlytapering conical opening 86 terminating in an opening 88 through whichthe lead wire 16 is passed. The hole in the thimble is centered over thecenter of the peg associated with the head on which the guide ismounted. In this manner and by the aid of the guide and the bulbcentering arms 48 and 52 it is possible to insure proper coaxialarrangement of the wafer stem, mount, bulb and top lead-in beforesealing parts together.

Having thus described the invention, what is claimed is:

In a machine for sealing leads into a bulb and wherein the machine has arotatable head and also a peg for rotatably supporting and verticallymoving an assembly of wafer stem with its electrode mount and a bulb,the mount having a lead supported by an electrode element within thebulb which lead extends loosely through a central opening in the top ofthe bulb, means including bulb engaging arms mounted on the head forcentering the bulb with respect to the wafer stem, the improvementcomprising means for centering the lead with reference to the bulbopening, said last means comprising a support mounted on said head androtatably therewith and with reference to which the peg is verticallymovable, and an axially apertured conical element fixedly supported bythe support in a position axially of the longitudinal axis of therotatable head and at all times above the bulb engaging arms, with theconical element tapering upwardly to guide the lead into the aperture ofthe conical element when the assembly approaches the head.

References Cited in the file of this patent UNITED STATES PATENTSFinland Dec. 31, 1953

